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Upcoming Syllabus (middle third) 24 Feb KB – Fungi Chapter 31 26 Feb KB – Prokaryotes, Protists, Photoautotrophy, Endosymbioses Chapters 28, 29 3 Mar KB – Plant Diversity Chapter 30 5 Mar KB – Plant Form and Function Chapters 36, 37 Diversity of Fungi 10 Mar KB – Plant Function Chapters 38, 40, and 39 (pp. 857-866, 873-882, 887-888) 12 Mar WS - Population Growth and Regulation Chapter 52 (Freeman Ch31) 17&19 Mar Spring Recess 24 Mar KB – Plant Community Ecology, Disturbance, Succession Chapters 30, 53 26 Mar KB – Galapagos Case Study Wikelski 2000 and www.darwinfoundation.org/en/galapagos/marine www.darwinfoundation.org/en/galapagos/land Thanks to Joanna Masel 24 February 2009 ECOL 182R UofA K. E. Bonine VIDEOS 1 31 Mar Part 2. Discussion and Review. 02 Apr EXAM 2 2 Tree of Life Kevin Bonine 182 Office Hours 3.8 bya 10-noon Tuesdays BSE 113 2+ bya -also M 1-2 and W 11-noon-206 and 437 students have priority- Orange 3 4 5 6 Opisthokonts (Fungi and Animals are closely related) 1 How fungi live Chitin (tough but flexible nitrogen-containing polysaccharide) • All use absorptive nutrition, secreting digestive enzymes and absorbing the breakdown products • Most are saprobes (feed on dead matter) • Production of chitin is a shared derived trait for – fungi – choanoflagellates – animals – Earth’s main decomposers (with bacteria) – principal decomposers of cellulose & lignin – nutrient (re)cyclers • Evidence that fungi are closer to animals than plants 7 Cell structure of multicellular fungi • Some are parasites • A few are mutualists 8 Incomplete division into cells Cell-like compartments separated by septa (singular septum) Vegetative body = mycelium (plural mycelia) Composed of threadlike hyphae (singular hypha) 10 Fungus structure coenocytic hypha septate hypha Free movement of organelles, sometimes even nuclei, and other materials 11 Fungal hyphae attack a leaf • Hyphae may – disperse to look for nutrients – clump together to exploit a food source • Mushrooms are a fruiting (reproductive) structure • Most Unicellular fungi are called Yeast 12 Hyphae give a large surface:volume ratio, which helps with absorptive nutrition 13 2 Symbiotic fungi Symbiotic fungi Lichens are symbiotic associations of a fungus with a - unicellular photosynthetic eukaryote – cyanobacterium - or both Lichens are important pioneer species 14 Symbiotic fungi • Mycorrhizae are mutualistic associations of fungi and plant roots ! • The fungus obtains ea ar ce fa organic compounds, r su of ts while the plant is Lo provided with water and soil nutrients • Some plants can’t grow without them 15 Fungi increase surface area for nutrient and water absorption by plant EMF AMF Mycorrhizae = mutualistic associations of fungi and plant roots 16 17 Predatory fungus! Fungi are very important cyclers of nutrients. Especially Carbon, Nitrogen, Phosporus. 18 Fungus capturing a nematode worm 19 3 Fungal reproduction can be complex Alternation of Generations Haploid (N) (~gametes) • Sexual OR asexual • Life cycles distinguish 4/5 phyla Fertilization Diploid (2N) • When sex has not been observed, provisionally classified as imperfect fungi (aka deuteromycetes): ~ 25,000 species Meiosis 20 Alternation of Generations Sexual Reproduction Depicted Here (Meiosis & Fertilization) Haploid (N) Etc. 21 Haplontic life cycle • Haploid is dominant, multicellular structure • Often diploid only very briefly as a zygote • Meiosis produces haploid nuclei again • Haploid spores divide mitotically to form haploid hyphae Both the haploid and the diploid have multicellular forms. Compare to Haplontic and Diplontic. 22 23 Dikaryotic Lifestage Chytrids (no dikaryote) Zygomycetes • Unique to fungi Dikaryotic stage • Two haploid (n) cells fuse, but not their nuclei = n + n dikaryote • Plasmogamy (cell fusion) followed later by Karyogomy to produce Alternation of generations Ascomycetes Haplontic Basidiomycetes Diploid (2n) Zygote Haplontic 24 Dikaryotic stage Haplontic Dikaryotic stage 25 Basidiocarp 4 Chytrid Fungi A chytrid fungus (Batrachochytrium dendrobatidis; Bd) has been implicated in the worldwide decline of numerous amphibian species. Frogs infected with this fungus suffer chytridiomycosis, a disease affects amphibian skin and is often fatal. Chytrid zoospores can survive in damp conditions and may be transported between frog populations in muddy clothing and footwear. - water balance - respiration - immune system 26 African Clawed Frog? 27 Asexual reproduction via spores Yeast are fungi • All five fungal phyla have unicellular species • Those of all phyla except chytrids are called yeasts • The yeast Saccharomyces cerevisiae makes CO2 and ethanol during fermentation • Used for bread and beer 28 Fungal spores are everywhere • Every breath we take is full of fungal spores (~10,000/m3 of air) Production of haploid spores within sporangia Production of naked spores at the tips of hyphae (not within sporangia) called 29 conidia Plants are not so lucky Parasitic fungus Ustilago maydis (corn smut) • Most humans only succumb to fungal pathogens when immunocompromised Fungus (aka mold, mildew, etc.) causes lots of crop damage - Dutch Elm disease - Chestnut blight sporotrichosis ring worm some pneumonias 30 31 5 Neither was this ant Fungal asexual reproduction • Cell division by unicellular fungi Spores of this fungus don’t germinate until ingested by an ant 32 • Simple breakage of the mycelium 33 Basidiomycete life cycle Fungal Sexual reproduction • Some fungi have more than 2 mating types • Mating types don’t look different • Mating can only occur between different mating types, preventing self-fertilization • Sexual reproduction when hyphae (or motile cells in chytrids) of different mating types meet and fuse 34 Basidiospores Basidiospores give rise to haploid hyphae. Haploid hyphae of + Mating type different mating types fuse, forming dikaryotic hyphae. Mycelial - Mating type hyphae Dikaryotic The basidium mycelium is the Young characteristic basidiocarp sexual reproductive Gills lined structure of the Pileus with basidia basidiomycetes. Basidiospores Basidiospores form The basidiocarp outside the basidium. is topped by a cap, or pileus, which has Basidiocarp gills on its underside. (fruiting structure) Nuclei Fused nucleus Basidium ms Basidia develop on the roo h s surfaces of the gills. 36 Nuclear fusion and meiosis Mu take place in the developing basidium. Important points about sex and reproduction Basidiomycete life cycle oom shr Mu – equal division (fission) – production of a daughter cell (budding) s 37 • Sex = 2 nuclei fusing and undergoing meiosis • Reproduction = one individual giving rise to multiple: can be sexual or asexual • Genetic recombination = any gene exchange: not just sex, also nonreproductive processes such as conjugation • Dikaryotic individuals include 2 fused individuals, but not fused nuclei • “Spores” can be sexual or asexual, reproductive or not: normally a small, tough cell with potential to become new organism. Often capable of latency. Can be plant, bacterial, protist or fungal. 39 6 Five Fungi Phyla Chytrids 1+ bya ~Aquatic Only fungi group with flagella Includes Batrachochytrium dendrobatidis (Bd) causing amphibian die-offs 40 Glomerocytes 41 Ascomycetes Important mycorrhizae associations with plants 42 Includes brewer’s and baker’s yeast. Lots of plant parasites. Molds and Mildew. Penicillin. Stinky cheese production. 43 Basidiomycetes Named after basidiocarp, Which we know as a mushroom 44 7